Gold Plating from the Acid Cyanide System: Some Aspects of the Effect of Plating Parameters on Codeposition

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Abstract
The effect of bath parameters such as temperature, agitation, current density and pH on the co-deposition of organic material and cobalt in the acid gold cyanide system has been examined and is described in this paper. In solutions producing deposits essentially identical to those produced from proprietary electrolytes it is shown that the codepositing metal and organic matter are directly linked. The importance of rigorous control of all parameters to produce a uniform deposit is emphasized. A qualitative link between organic codeposition and electroplate stress, brightness and porosity is illustrated. A gold deposit from the acid cyanide bath containing less than about 0–07% wt carbon originating as cyanide is dull irrespective of the quantity of ‘brightener’ metal codepositing, indicating that the cyanide is functioning as a grain refining agent and stress modifier in a similar fashion to organic brighteners in other electroplating systems.